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PostgreSQL Reference Manual - Volume 3 - Server Administration Guide
by The PostgreSQL Global Development Group
Paperback (6"x9"), 204 pages
ISBN 0954612043
RRP £13.95 ($24.95)

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4.5.3 Archiving

archive_command (string)
The shell command to execute to archive a completed segment of the WAL file series. If this is an empty string (the default), WAL archiving is disabled. Any %p in the string is replaced by the path name of the file to archive, and any %f is replaced by the file name only. (The path name is relative to the working directory of the server, i.e., the cluster's data directory.) Use %% to embed an actual % character in the command. For more information see section 10.3.1 Setting up WAL archiving. This parameter can only be set in the ‘postgresql.conf’ file or on the server command line. It is important for the command to return a zero exit status if and only if it succeeds. Examples:
archive_command = 'cp "%p" /mnt/server/archivedir/"%f"'
archive_command = 'copy "%p" /mnt/server/archivedir/"%f"'
  # Windows
archive_timeout (integer)
The archive_command is only invoked on completed WAL segments. Hence, if your server generates little WAL traffic (or has slack periods where it does so), there could be a long delay between the completion of a transaction and its safe recording in archive storage. To put a limit on how old unarchived data can be, you can set archive_timeout to force the server to switch to a new WAL segment file periodically. When this parameter is greater than zero, the server will switch to a new segment file whenever this many seconds have elapsed since the last segment file switch. Note that archived files that are closed early due to a forced switch are still the same length as completely full files. Therefore, it is unwise to use a very short archive_timeout---it will bloat your archive storage. archive_timeout settings of a minute or so are usually reasonable. This parameter can only be set in the ‘postgresql.conf’ file or on the server command line.
ISBN 0954612043PostgreSQL Reference Manual - Volume 3 - Server Administration GuideSee the print edition